The gunman who charged into one of the Pentagon's main entrances and opened fire has died from gunshot wounds to the head and authorities are looking into his recent rants against the government as a potential motive.
John Patrick Bedell, 36, died at the hospital Thursday night after Pentagon police returned fire. Police told ABC News that the two police officers wounded in the shooting have been released from the hospital after suffering minor injuries. They are now on administrative leave pending the investigation of the incident, police said.
The attack seems to be another suicide mission aimed at the government. While police have said they are not certain of a motive, they are investigating Internet postings in which Bedell wrote and recorded audio expressing his anger toward the government.
"The moral values of individuals and communities are increasingly attacked by a political system where deceit is routine and accepted and the only standard is power," he said in the online video.
Authorities say Bedell's had brushes with the law in the past and his Internet musing mentioned charges for marijuana possession as a reference to the government's intervention in his life.
The shooting came just weeks after Joe Stack flew his plane into the IRS office in Austin, Texas, after leaving a lengthy manifesto in which he told the IRS to "take my pound of flesh and sleep well."
Bedell opened fire at 6:40 p.m. Thursday after officers asked him for an access pass, police said.
"It came at the time of night when thousands of Pentagon employees were trying to leave the building at one of the Pentagon's main entrances," ABC News correspondent Martha Raddatz told "Good Morning America's" George Stephanopoulos.
ABC News' Luis Martinez was inside the Pentagon when the shooting started. As a building-wide announcement notified workers that the Metro had been locked down, employees began trying to make their way to various exits only to find each one blocked.
"I headed towards one of those exits as the building operations center is located nearby. That's when I started to see a backlog of people milling the length of the corridor to the exit," Martinez said. "They'd just been told that those exits had been closed as well and that the building was locked down."
The officers that were shot, he said, were manning an open-air checkpoint where people with badges can walk in without having to go through security.
Pentagon Police Chief Richard S. Keevill said that the gunman appeared to have acted alone. He was carrying two 9 mm semi-automatic guns and many magazines of ammunition, according to police.
Keevill said there was "no indication at this point [of] any domestic or international terrorism at all."
Pentagon Gunman Dressed in a Suit Calmly Opened Fire
Keevill said Bedell was "dressed in a suit and gave no indication of hostile intent, a very well-dressed individual. He was very calm, no distress. Walked directly up to the officers and engaged them."
He also said that he may have uttered something before opening fire, but what he said was unclear at this time.
Bedell drove to Washington, D.C., from California over the past few weeks, Keevill said, adding that police have been able to trace his movements as he made his way. He parked his vehicle in a local garage; it has since been impounded and is being processed.
The officers belonged to the Pentagon Force Protection Agency, the Defense Department said in a statement.
Police also confirmed today that a second individual taken into custody was only briefly detained and was released after authorities determined that he had nothing to do with the incident.
In response to a question, police said there was no need to change the police training procedures because the Fort Hood shooting last year "put us on notice this could even happen at a military reservation." He said police had the appropriate training and procedure in place and doesn't foresee a change "in how we do business."
Initially, hundreds of employees at the Pentagon were ordered to go into "Code Red" -- the entire building locked down, with no one allowed to enter or leave.
At least three ambulances were seen at the location last night, and all parking lots at the massive Defense Department headquarters were closed off.
After about 45 minutes, people were allowed to leave the Pentagon building through entrances other than the one closest to the Metro station, though Metro trains bypassed the Pentagon station.
Service to the station resumed around 8 p.m. Thursday, according to a statement by Metro officials, though parts of the facility will remain closed as it is "a very complicated crime scene" with a lot of bullets, according to police.
Video Footage of Shooter Will Not Be Released Yet
Police are examining surveillance footage of the incident, which lasted under a minute, but said it will not be released any time soon.
This is not the first case of a fatal Pentagon shooting, Keevill said, adding that in the late 1980's a person with mental issues came on the reservation and shot a Naval officer, but "that was many years ago before 9/11."
The Pentagon Metro station stop is a couple of hundred feet from the famous five-sided building, which was hit by a passenger jet during the 9/11 terror attacks. People leaving the station who wish to enter the Pentagon must show ID to Pentagon police in order to get close to the building.
The Pentagon, just across the Potomac River from downtown Washington, is, by area, the world's largest office building. About 26,000 people work there, according to the Defense Department.
ABC News' Jason Ryan, Sarah Netter, Steven Portnoy and Jennifer Wlach, and Reuters contributed to this story.